Faulted circuit indicators (FCIs) are used in the field of electric power distribution systems. Generally, FCIs are electrically connected to transmission lines in a power distribution system at various locations throughout the system, often in close proximity to system loads. When a fault occurs in a transmission line, FCIs between the fault and the source will detect that a fault has occurred. Typically, FCIs that have detected a fault then display an indication that the fault has been detected. A technician can then identify a fault by locating the transmission line between an FCI that indicates it has detected a fault and an FCI that displays no such indication.
Because of their binary nature, conventional FCIs provide little assistance in locating a transient or intermittent fault. Generally, conventional FCIs are reset either by a manual trigger, wherein a technician manually manipulates the FCI to remove the fault indication, or by a current trigger, wherein if the FCI determines that conditions on the transmission line have returned to normal, the FCI automatically resets. In conventional FCIs, an automatic reset is a desirable feature because it ensures that the FCI only indicates existing faults, which reduces the likelihood that a false fault indication will increase the amount of time necessary for a technician to diagnose and repair an actual fault. However, an automatic reset results in an intermittent or transient fault triggering an FCI's indicator only for a short time, followed by an immediate reset of the indicator, making the location of a faulted FCI during the presence of a faulted condition nearly impossible.
Additionally, conventional FCIs cannot monitor other conditions on a transmission line that can pose risks to the life or performance of the transmission line and other related equipment. For example, power surges at certain levels can not be sufficient to result in a fault condition indicated by conventional FCIs. However, such power surges can shorten the life of a transmission line that experiences those surges and any transformers or other equipment attached to that line. Additionally, conditions such as excess heat or vibration on a line can indicate a problem on a transmission line that, with the use of conventional FCIs, cannot be detected until a fault occurs, potentially resulting in a loss of service for customers that might have been avoided had the condition been diagnosed earlier.
Finally, when a fault occurs, the only way to determine which portion of a transmission line contains the fault in conventional systems is to send technicians to the general vicinity of a power outage to search for FCIs that indicate a fault. Because transmission lines often are located underground, this design can require the technicians to travel from FCI to FCI on foot until they locate the first faulted FCI. Thus, even with the help of FCIs, the process of locating a fault can be time consuming, resulting in increased costs to the electrical utility company servicing the fault, as well as extended periods of outages for their customers.
Conventional FCIs are not capable of determining and transmitting the state of a transmission line, nor are conventional FCIs capable of transmitting fault information and state information relating to a transmission line to a remote location.
Accordingly, a need exists in the art for an FCI that is capable of monitoring multiple line conditions, including simple current flow, to assist in the determination of unfavorable conditions, storing historical fault and line state information to assist in the diagnosis of transient and intermittent faults, and communicating fault and line state information to a remote location to reduce the time needed to recover from a fault event.